Pyrolysis and Deposition Mechanism of Poly (vinylidene fluoride) in Vacuum Deposition Process

• Published in: KOBUNSHI RONBUNSHU Vol. 48; no. 7; pp. 399 - 404
• Main Authors: TAKENO, Akiyoshi, OKUI, Norimasa, HIRUMA, Toshimitsu, KITOH, Tetsuji, MURAOKA, Michiharu, UMEMOTO, Susumu, SAKAI, Tetsuya
• Format: Journal Article
• Language: English; Japanese
• Published: The Society of Polymer Science, Japan 01.01.1991
• Subjects: Molecular Weight; Oligomer; Poly (vinylidene fluoride); Thermal Decomposition; Thin Film; Vacuum Deposition
• ISSN: 0386-2186; 1881-5685
• DOI: 10.1295/koron.48.399

During the vacuum deposition process for polymeric materials, the polymer chains are pyrolyzed and subsequently evaporated. In this paper, the thermal decomposition behavior of poly (vinylidene fluoride: PVdF) in a vacuum chamber and the deposition mechanism onto the substrate were studied. PVdF was evaporated onto the Si wafers as a function of the evaporation crucible temperature, the substrate temperature and the distance from crucible to the substrate. At the crucible temperatures above 300°C, the thermal-decomposition of PVdF chains occurred and the molecular weight decreased to less than 2700. However, below 300°C, the low molecular weight fraction (Mn-460) contained in the original PVdF was evaporated without any thermal decompositions. PVdF was significantly decomposed and was carbonized in the crucible maintained at the temperatures above 350°C. The molecular weight and the distribution for the deposited films could be controlled by the crucible temperature, the substrate temperature and the distance from the crucible to the substrate. For example, the molecular weight of the films decreased with a rise in the substrate temperature and/or with an increase in the distance. The films obtained at a substrate temperature of 125°C had a number average molecular weight of Mn=460 and a molecular weight distribution of Mw/Mn=1.03.